Malaysian NGOs, well-known bloggers and opposition politicians on Tuesday staged a one-day \"Internet blackout\" to protest a legal amendment that they say threatens free expression on the Web. Participants replaced their home pages with black screens featuring messages attacking the new section of the Evidence Act, which went into effect in April despite widespread opposition. Critics say under the amendment any web host, provider of a wi-fi network, or ordinary user of a computer or mobile device can be found liable for any defamatory or harmful Web content sent via its systems. Activists have called it an attempt by the ruling coalition government, which has been in power for more than five decades, to clamp down on the Internet. Prime Minister Najib Razak must call elections by next year against a formidable opposition that gets most of its message out via the Internet due to a government stranglehold on traditional media. The government promised in the 1990s not to censor the Internet in a bid to draw in foreign high-tech investment, although authorities are accused of blocking some sites. The effort has been spearheaded by Malaysia\'s Centre for Independent Journalism (CIJ), which calls the amendment \"a bad law passed in haste and does not take into account public interest and participation.\" The CIJ and other critics -- which also have included some figures in the ruling coalition -- have called for it to be scrapped or revised. The 24-hour blackout was to last until midnight. Users attempting to access Paultan.org, a highly popular automotive-themed blog, were greeted with with a black pop-up screen that said \"This is what the web could look like\" under the legal change. Malaysia has long been known for its authoritarian rule but Najib, who came to power in 2009, has launched a campaign to repeal some repressive laws to gain voter support. However, the opposition and rights groups have dismissed the drive as a sham, saying that various laws introduced to replace the previous legislation have been little better than the old statutes.